Android - Application Framework

1. Android –
Application Framework
Yong Heui Cho @ Mokwon University
Some of slides are referred to:
[1] Nitin Ramchandani, Android OS, slideshare.
[2] Luca Bedogni & Marco Di Felice, Programming with Android: System
Architecture, SlidePlayer.

2. 2
Smart Device Structure
2. Android Studio Tutorial
3. Basic Android OS
4. Android – Application
Framework
5. Android – Message

3. 3

4. 4
Libraries (I)
• Media Libraries - based on PacketVideo's OpenCORE;
the libraries support playback and recording of many
popular audio and video formats, as well as static
image files, including MPEG4, H.264, MP3, AAC, AMR,
JPG, and PNG
• LibWebCore - a modern web browser engine
which powers both the Android browser and an
embeddable web view
□ Courtesy to Nitin Ramchandani, Android OS, slideshare.

5. 5
• SGL (Skia GL) - the underlying 2D graphics
engine
• 3D libraries - an implementation based on
OpenGL ES 1.0 APIs; the libraries use either
hardware 3D acceleration (where available) or
the included, highly optimized 3D software
rasterizer
• FreeType - bitmap and vector font rendering
• SQLite - a powerful and lightweight relational
database engine available to all applications
Libraries (II)
□ Courtesy to Nitin Ramchandani, Android OS, slideshare.

6. 6
•Set of standardized APIs the developer will have to
implement
•Available for all the components a manufacturer can
integrate on its Android platform
Defines the interface that Android requires
hardware “drivers” to implement.
HW Abstraction Layer
□ Courtesy to Nitin Ramchandani, Android OS, slideshare.

7. 7
• Android includes a set of core libraries that
provides most of the functionality available in
the core libraries of the Java programming
language
Core Libraries
□ Courtesy to Nitin Ramchandani, Android OS, slideshare.

8. 8
Dalvik Virtual Machine
□ Courtesy to Nitin Ramchandani, Android OS, slideshare.
Before Android 5.0 Lollipop
• Designed for embedded environment
• Supports multiple VM processes
per device.
• Highly CPU-optimized byte code
interpreter.
• Uses run time memory very efficiently.
• Run optimized file format (.dex) Dalvik bytecode.
• Java .class/.jar are converted to .dex at build time.

9. 99
Dalvik Java Virtual Machine
Java Source
Code
Java Byte
Code
Java Virtual
Machine
(JVM)
Java Source
Code
Java Byte
Code
Dalvik Byte
Code
Dalvik Virtual
Machine
(DVM)
Java
Compiler
Java
Compiler
Dex
Compiler
Stack-based
byte-code
Register-based
byte-code
Java Standard Edition
□ Courtesy to L. Bedogni & M. Di Felice, Programming with Android, SlidePlayer.

10. 10
Android Runtime (ART)
• After Android 5.0 Lollipop
• ART introduces the use of ahead-of-
time (AOT) compilation by compiling
entire applications into native machine
code upon their installation.
– Faster execution of applications
– Improved battery time
– Improved memory allocation and garbage
collection

11. 11
Comparison of ART & DVM

12. 12
Application Framework (I)
•A Notification Manager that enables all
applications to display custom alerts in the status
bar
•An Activity Manager that manages the lifecycle of
applications and provides a common navigation
backstack
□ Courtesy to Nitin Ramchandani, Android OS, slideshare.

13. 13
• A rich and extensible set of Views that can be used
to build an application, including lists, grids, text
boxes, buttons, and even an embeddable web
browser
• Content Providers that enable applications to access
data from other applications (such as Contacts), or to
share their own data
• A Resource Manager providing access to non-code
resources such as localized strings, graphics, and
layout files
Application Framework (II)
□ Courtesy to Nitin Ramchandani, Android OS, slideshare.

14. 14
1.Activities
2.Intent
3.Services
4.Content Providers
Important App Components

15. 15
•Activity is an User Interface Screen.
•An application may have two or more activities to handle
different phases of program.
For e.g. opening page, menu page, etc.
•Activity is responsible for saving its own state so that it can be
restored later as part of the application life cycle.
Activities
□ Courtesy to Nitin Ramchandani, Android OS, slideshare.
single activity multiple activities

16. 16
•Intent is a mechanism for describing a specific action
such as pick a photo.
•Basically we register an Activity to handle an Intent.
Intents
□ Courtesy to Nitin Ramchandani, Android OS, slideshare.

17. 17
•A content provider is a set of data wrapped up in a
custom API to read and write it. This is the best way
to share global data between applications.
•Google provide content provider for contacts.
Content Provider
□ Courtesy to Nitin Ramchandani, Android OS, slideshare.

18. 18
•A service is a task that runs in the background
without the user’s direct interaction, similar to a Unix
daemon.
For e.g. we can have Music player program playing in
background even if we are browsing other programs.
Services
□ Courtesy to Nitin Ramchandani, Android OS, slideshare.

19. 19
•Can combined 2D and 3D surfaces
•Can use OpenGL ES and 2D hardware accelerator for its
compositions
Provides a system-wide surface “composer” to render
all the surfaces in a frame buffer
Surface Manager
□ Courtesy to Nitin Ramchandani, Android OS, slideshare.

20. 20
•Handle several types of devices (headphone,
ear piece…)
•Redirects audio stream to the specified output
Audio Manager
□ Courtesy to Nitin Ramchandani, Android OS, slideshare.

21. 21
Fragment
• A piece of an application's UI or
behavior that can be placed in an
Activity

22. 22
Android App Design
 GUI Definition
 Events Management
 Application Data Management
 Background Operations
 User Notifications
APPLICATION DESIGN:
□ Courtesy to L. Bedogni & M. Di Felice, Programming with Android, SlidePlayer.